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August 17th, 2016

Not too distant in future, new generation would not know how visceral a feeling it was to drive an internal combustion engine. It is on it’s way out; with emission concerns growing, electric is the future. Now, the Japanese automaker, Infiniti has decided to shake up our understanding of the IC engine. The Infiniti VC-T , or Variable Compression engine technology brings a paradigm shift in variable displacement engine philosophy and it is extremely smart.

A technology that took over 20 years and over 300 patents in the making, the Infiniti VC-T engine is Nissan’s answer to a long lasting quest into variable displacement technology. Among the most critical engine design parameters is its compression ratio. It is also among the very first things that engineers set for a new engine design. Compression ratio dictates not only how much power you make, but how you can make it; with or without boost. And therein lays the spectacular smartness of this new Infiniti VC-T engine. It can actually vary the compression ratio according to the driving conditions on the go. Achieving this basically means that Nissan and Infiniti have effectively re-drawn the engine design strategies, forever.

Infiniti Variable Compression Engine

Presently, most modern engines use cylinder de-activation technology to temporarily give a smaller, more efficient engine. It is also used by a large number of manufacturers, from Honda to the likes of Aston Martin and Bentley. However, The Infiniti VC-T does things more cleverly. What Infiniti VC-T engine does is to change the stroke of the pistons automatically depending on the driving situation. This clever engineering leads to varying of the displacement and compression ratio of the engine.

How Infiniti VC-T Engine Functions:

The Infiniti VC-T features two connecting rods attached to opposite sides of a metal plate. This metal plate rotates around a journal on the crankshaft, which is mounted mid-way up the block. The top end of the upper connecting rod is connected to the piston in the conventional manner. The lower end is connected to one side of the plate. The upper end of the lower connecting rod is attached to the opposite side of the plate, and the lower end is attached to an eccentric shaft mounted below the crank.

An actuator link rotates the eccentric shaft, moving the lower connecting rod up or down. This movement in turn rotates the plate around its axis on the crankshaft. The corresponding motion on the other side of the plate lowers or raises the lower connection point of the upper connecting rod. This lowers or raises the top dead center position of the piston, effectively changing the compression ratio.

Variable Compression Engine

As per engineers, the Infiniti VC-T can vary the compression ratio seamlessly and continuously between 8:1 and 14:1. For hard acceleration or heavy loads to allow the turbocharger to deliver maximum boost, the engine will adopt a lower compression ratio. The engine, on the other hand, will have a higher compression ratio for fuel-efficient and lean-burn run. The engine, which uses both port and direct injection, will switch between Atkinson and regular combustion cycles without interruption. In the Infiniti VC-T, the Inlet valve timing is controlled electronically.

Engineers say the engine is cheaper to build than a Euro 6 compliant diesel, and it won’t be subject to the growing backlash against diesels in Europe because of increased concerns over particulate emissions. Power output from this inline four is expected to be around 270bhp with Diesel-rivaling fuel efficiency. Interestingly, it is being claimed that the Infiniti VC-T is 27% more fuel efficient than the company’s 3.5-litre V6. This should mean that the new Infiniti VC-t In-line four will replace the V6 unit.

You can understand the functioning of this engine better from the video below. As always do let us know what you think in the comments section below.

Infiniti VC-T Engine

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